Can simple models describe the phase diagram of water?

The melting point of ice I-h for the TIP3P, SPC, SPC/E, TIP4P, TIP4P/Ew and TIP5P models has been determined by computer simulation. It has been found that the melting points Of ice Ih for these models are 146, 190, 215, 232, 245 and 274 K respectively. Thus from the models of water available so far only TIP5P reproduces the experimental melting point of water. The relative stability of ice 11 with respect to ice Ih at the normal melting point has also been considered. Ice 11 is more stable than ice Ih for the TIP3P, SPC, SPC/E and TIP5P models. Only for the TIP4P and TIP4P/Ew models is ice Ih more stable than ice 11 at low pressures. The complete phase diagram for the SPC/E, TIP4P and TIP5P models has been computed. It has been found that SPC/E and TIP5P do not correctly describe the phase diagram of water. However, TIP4P provides a qualitatively correct description of the phase diagram of water. A slight modification of the parameters of the TIP4P model yields a new model, denoted as TIP4P/ice, which reproduces the experimental melting point of water and provides an excellent description of the densities of all ice phases.